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The once abundant, but now seriously depleted, Atlantic salmon in Maine were listed as endangered under the federal Endangered Species Act in November 2000. This report covers the wild fish in eight Maine rivers as a single &amp;amp;quot;distinct population segment.&amp;amp;quot; The controversy in Maine that accompanied the listing led Congress to ask the National Academies' advice on the science relevant to understanding and reversing the declines in Maine's salmon population. As requested by Congress, this interim report focuses on the genetic makeup of Maine Atlantic salmon populations.

Key Messages

Maine streams have salmon populations that are genetically as divergent from Canadian salmon populations and from each other as would be expected in natural salmon populations anywhere else in the Northern Hemisphere.

North American Atlantic salmon are clearly distinct genetically from European salmon.

The evidence is surprisingly strong that the wild salmon in Maine are genetically distinct from Canadian salmon.

There is considerable genetic divergence among populations in the eight Maine rivers where wild salmon are found.